Materials Science And Engineering An Introduction doc

Processing/Structure/Properties/Performance Correlations One new feature that has been incorporated throughout this new edition is a ing of relationships among the processing, structure,

Characteristics of Selected Elements

Atomic Density of Crystal Atomic Ionic Most Melting Atomic Weight Solid, 20 ⬚C Structure, Radius Radius Common Point Element Symbol Number (amu) (g/cm 3) 20 ⬚C (nm) (nm) Valence (⬚C)

Values of Selected Physical Constants

8.62 ⫻ 10 ⫺5 eV/atom K

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page iv

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EI G H T H ED I T I O N

Materials Science and Engineering

An Introduction

William D Callister, Jr.

Department of Metallurgical Engineering

The University of Utah

David G Rethwisch

Department of Chemical and Biochemical Engineering

The University of Iowa

John Wiley & Sons, Inc.

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page iii

Front Cover: Depiction of a unit cell for the inverse spinel crystal structure Red spheres represent

O2⫺oxygen ions; dark blue and light blue spheres denote Fe2⫹and Fe3⫹iron ions, respectively (As cussed in Chapter 20, some of the magnetic ceramic materials have this inverse spinel crystal structure.)

dis-Back Cover: The image on the right shows the ionic packing of a close-packed plane for the inverse spinel

crystal structure The relationship between this close-packed plane and the unit cell is represented by the image on the left; a section has been taken through the unit cell, which exposes this close-packed plane.

VICE PRESIDENT AND EXECUTIVE PUBLISHER Donald Fowley

EDITORIAL PROGRAM ASSISTANT Alexandra Spicehandler PRODUCTION SERVICES MANAGER Dorothy Sinclair

EXECUTIVE MARKETING MANAGER Christopher Ruel

PRODUCTION SERVICES Elm Street Publishing Services

This book was set in Times Ten Roman 10/12 by Aptara, Inc., and printed and bound by World Color USA/Versailles The cover was printed by World Color USA/Versailles.

This book is printed on acid-free paper.

Copyright © 2010, 2007, 2003, 2000 John Wiley & Sons, Inc All rights reserved No part of this cation may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission

publi-of the Publisher, or authorization through payment publi-of the appropriate per-copy fee to the Copyright

Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, website www.copyright.com.

Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, (201) 748-6011, fax (201) 748-6008,

website www.wiley.com/go/permissions.

Evaluation copies are provided to qualified academics and professionals for review purposes only, for use in their courses during the next academic year These copies are licensed and may not be sold or transferred to a third party Upon completion of the review period, please return the evaluation copy

to Wiley Return instructions and a free of charge return shipping label are available at

www.wiley.com/go/returnlabel Outside of the United States, please contact your local representative.

Library of Congress Cataloging-in-Publication Data

Callister, William D., Materials science and engineering: an introduction / William D Callister, Jr., David G Rethwisch.–8th ed.

2009023130 L.C Call no Dewey Classification No L.C Card No.

ISBN 978-0-470-41997-7 (Main Book) ISBN 978-0-470-55673-3 (Binder-Ready Version)

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

q JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page iv

Dedicated to our wives, Nancy and Ellen, whose love, patience, and understanding

have helped make this volume possible

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page v

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page vi

In this Eighth Edition we have retained the objectives and approaches for

teach-ing materials science and engineerteach-ing that were presented in previous editions The first, and primary, objective is to present the basic fundamentals on a level appro-

priate for university/college students who have completed their freshmen calculus,chemistry, and physics courses In order to achieve this goal, we have endeavored

to use terminology that is familiar to the student who is encountering the discipline

of materials science and engineering for the first time, and also to define and plain all unfamiliar terms

ex-The second objective is to present the subject matter in a logical order, from

the simple to the more complex Each chapter builds on the content of previousones

The third objective, or philosophy, that we strive to maintain throughout the

text is that if a topic or concept is worth treating, then it is worth treating in cient detail and to the extent that students have the opportunity to fully understand

suffi-it wsuffi-ithout having to consult other sources; also, in most cases, some practical vance is provided Discussions are intended to be clear and concise and to begin atappropriate levels of understanding

rele-The fourth objective is to include features in the book that will expedite the

learning process These learning aids include:

• Numerous illustrations, now presented in full color, and photographs to helpvisualize what is being presented;

• Learning objectives, to focus student attention on what they should be gettingfrom each chapter;

• “Why Study ” and “Materials of Importance” items that provide relevance

• Answers to selected problems, so that students can check their work;

• A glossary, list of symbols, and references to facilitate understanding thesubject matter

The fifth objective is to enhance the teaching and learning process by using the

newer technologies that are available to most instructors and students of neering today

engi-• viiPreface

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page vii

FEATURES THAT ARE NEW TO THIS EDITION

New/Revised Content

Several important changes have been made with this Eighth Edition One of themost significant is the incorporation of a number of new sections, as well as revisions/amplifications of other sections New sections/discussions are as follows:

• Diffusion in semiconductors (Section 5.6)

• Flash memory (in Section 18.15)

• “Biodegradable and Biorenewable Polymers/Plastics” Materials of Importancepiece in Chapter 22

Other revisions and additions include the following:

• Expanded discussion on nanomaterials (Section 1.5)

• A more comprehensive discussion on the construction of crystallographicdirections in hexagonal unit cells—also of conversion from the three-indexscheme to four-index (Section 3.9)

• Expanded discussion on titanium alloys (Section 11.3)

• Revised and enlarged treatment of hardness and hardness testing of ics (Section 12.11)

ceram-• Updated discussion on the process for making sheet glass (in Section 13.9)

• Updates on magnetic storage (hard disk drives and magnetic tapes—Section20.11)

• Minor updates and revisions in Chapter 22 (“Economic, Environmental,and Societal Issues in Materials Science and Engineering”), especially onrecycling

• Appendix C (“Costs and Relative Costs for Selected Engineering Materials”)

has been updated

• End-of chapter summaries have been revised to reflect answers/responses to

the extended lists of learning objectives, to better serve students as a studyguide

• Summary table of important equations at the end of each chapter.

• Summary list of symbols at the end of each chapter.

• New chapter-opener photos and layouts, focusing on applications of materials

science to help engage students and motivate a desire to learn more aboutmaterials science

• Virtually all Homework problems requiring computations have been refreshed Processing/Structure/Properties/Performance Correlations

One new feature that has been incorporated throughout this new edition is a ing of relationships among the processing, structure, properties, and performancecomponents for four different materials: steel alloys, glass-ceramics, polymer fibers,and silicon semiconductors.This concept is outlined in Chapter 1 (Section 1.7), whichincludes the presentation of a “topic timeline.” This timeline notes those locations(by section) where discussions involving the processing, structure, properties, andperformance of each of these four material types are found

track-These discussions are introduced in the “Why Study?” sections of appropriatechapters, and, in addition, end-of-chapter summaries with relational diagrams arealso included Finally, for each of the four materials a processing/structure/properties/

viii • Preface

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page viii

performance summary appears at the end of that chapter in which the last item onthe topic timeline appears.

All Chapters Now In Print

Five chapters of the previous edition were in electronic format only (i.e., not in

print) In this edition, all chapters are in print.

Case Studies

In prior editions, “Materials Selection and Design Considerations” consisted of aseries of case studies that were included as Chapter 22 These case studies willnow appear as a library of case studies on the book’s web site (Student Compan-

ion Site) at www.wiley.com/college/callister This library includes the following:

• Materials Selection for a Torsionally Stressed Cylindrical Shaft

• Automobile Valve Spring

• Failure of an Automobile Rear Axle

• Artificial Total Hip Replacement

• Chemical Protective Clothing

• Materials for Integrated Circuit Packages

STUDENT LEARNING RESOURCES

(WWW.WILEY.COM/COLLEGE/CALLISTER)

Also found on the book’s web site (Student Companion Site) are several tant instructional elements for the student that complement the text; these includethe following:

impor-1 VMSE: Virtual Materials Science and Engineering This is an expanded

ver-sion of the software program that accompanied the previous edition It consists ofinteractive simulations and animations that enhance the learning of key concepts inmaterials science and engineering, and, in addition, a materials properties/cost data-

base Students can access VMSE via the registration code included on the inside

front cover of the textbook

Throughout the book, whenever there is some text or a problem that is

supple-mented by VMSE, a small “icon” that denotes the associated module is included in

one of the margins These modules and their corresponding icons are as follows:Metallic Crystal Structures

Phase Diagramsand Crystallography

Ceramic Crystal Structures DiffusionRepeat Unit and Polymer

Tensile TestsStructures

Preface • ix

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page ix

2 Answers to Concept Check questions Students can visit the web site to find

the correct answers to the Concept Check questions

3 Extended Learning Objectives—a more extensive list of learning objectives

than is provided at the beginning of each chapter These direct the student to studythe subject material to a greater degree of depth

4 Direct access to online self-assessment exercises This is a Web-based

assess-ment program that contains questions and problems similar to those found in thetext; these problems/questions are organized and labeled according to textbook sec-tions An answer/solution that is entered by the user in response to a question/problem

is graded immediately, and comments are offered for incorrect responses The studentmay use this electronic resource to review course material, and to assess his/hermastery and understanding of topics covered in the text

5 Index of Learning Styles Upon answering a 44-item questionnaire, a user’s

learning style preference (i.e., the manner in which information is assimilated andprocessed) is assessed

INSTRUCTORS’ RESOURCES

The Instructor Companion Site (www.wiley.com/college/callister) is available for

in-structors who have adopted this text Please visit the web site to register for access.Resources that are available include the following:

1 Instructor Solutions Manual Detailed solutions of all end-of-chapter

ques-tions and problems (in both Word® and Adobe Acrobat® PDF formats)

2 Photographs, illustrations, and tables that appear in the book These are in

both PDF and JPEG formats so that an instructor can print them for handouts orprepare transparencies in his/her desired format

3 A set of PowerPoint® lecture slides These slides, developed by Peter

M Anderson (The Ohio State University), and adapted by the text authors, low the flow of topics in the text, and include materials from the text and fromother sources Instructors may use the slides as is or edit them to fit their teach-ing needs

fol-4 A list of classroom demonstrations and laboratory experiments These

portray phenomena and/or illustrate principles that are discussed in the book;references are also provided that give more detailed accounts of these demon-strations

5 Conversion guide This guide notes, for each homework problem/question (by number), whether or not it appeared in the seventh edition of Introduction, and,

if so, its number in this previous edition Most problems have been refreshed (i.e.,new numbers were assigned to values of parameters given the problem statement);refreshed problems are also indicated in this conversion guide

6 Suggested course syllabi for the various engineering disciplines Instructors

may consult these syllabi for guidance in course/lecture organization and planning

7 In addition, all of the student learning resources described above are able on the Instructor Companion Site

Personalize the learning experience

Different learning styles, different levels of proficiency, different levels of preparation—

each of your students is unique WileyPLUS empowers them to take advantage of

their individual strengths:

• Students receive timely access to resources that address their demonstratedneeds, and get immediate feedback and remediation when needed

• Integrated, multi-media resources—including visual exhibits, demonstrationproblems, and much more—provide multiple study-paths to fit eachstudent’s learning preferences and encourage more active learning

• WileyPLUS includes many opportunities for self-assessment linked to the

relevant portions of the text Students can take control of their own ing and practice until they master the material

learn-For Instructors

Personalize the teaching experience WileyPLUS empowers you, the instructor, with the tools and resources you need

to make your teaching even more effective:

• You can customize your classroom presentation with a wealth of resourcesand functionality from PowerPoint slides to a database of rich visuals You

can even add your own materials to your WileyPLUS course.

• With WileyPLUS you can identify those students who are falling behind and

intervene accordingly, without having to wait for them to come to your office

• WileyPLUS simplifies and automates such tasks as student performance

assessment, making assignments, scoring student work, recording grades, andmore

FEEDBACK

We have a sincere interest in meeting the needs of educators and students in thematerials science and engineering community, and, therefore, would like to solicitfeedback on this eighth edition Comments, suggestions, and criticisms may be sub-

mitted to the authors via e-mail at the following address: billcallister@comcast.net.

Appreciation is expressed to those who have made contributions to this tion We are especially indebted to Michael Salkind of Kent State University, whoprovided assistance in updating and upgrading important material in several chap-ters In addition, we sincerely appreciate Grant E Head’s expert programming skills,

edi-which he used in developing the Virtual Materials Science and Engineering software.

In addition, we would like to thank instructors who helped in reviewing the

manu-script, who reviewed and have written content for WileyPLUS, and, in addition,

oth-ers who have made valuable contributions:

Arvind Agarwal Florida International UniversitySayavur I Bakhtiyarov New Mexico Institute of Mining and TechnologyPrabhakar Bandaru University of California-San Diego

Valery Bliznyuk Western Michigan UniversitySuzette R Burckhard South Dakota State UniversityStephen J Burns University of Rochester

Matthew Cavalli University of North DakotaAlexis G Clare Alfred University

Stacy Gleixner San José State UniversityGinette Guinois Dubois AgrinovationRichard A Jensen Hofstra University

Kathleen Kitto Western Washington UniversityChuck Kozlowski University of Iowa

Masoud Naghedolfeizi Fort Valley State University

Oscar J Parales-Perez University of Puerto Rico at Mayaguez

Sandie Rawnsley Murdoch University

Hans J Richter Seagate Recording Media

Jeffrey J Swab U.S Military AcademyCindy Waters North Carolina Agricultural and Technical State

UniversityYaroslava G Yingling North Carolina State University

We are also indebted to Jennifer Welter, Sponsoring Editor, for her assistanceand guidance on this revision

Last, but certainly not least, the continual encouragement and support of ourfamilies and friends is deeply and sincerely appreciated

WILLIAMD CALLISTER, JR.

DAVIDG RETHWISCH JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xii

L IST OF S YMBOLS xxi

1 Introduction

Learning Objectives 21.1 Historical Perspective 21.2 Materials Science and Engineering 31.3 Why Study Materials Science and Engineering? 51.4 Classification of Materials 5

Materials of Importance—Carbonated Beverage Containers 10

1.5 Advanced Materials 111.6 Modern Materials’ Needs 131.7 Processing/Structure/Properties/Performance Correlations 14

Summary 16 References 17 Question 17

Learning Objectives 192.1 Introduction 19

A TOMIC S TRUCTURE 19

2.2 Fundamental Concepts 192.3 Electrons in Atoms 202.4 The Periodic Table 26

A TOMIC B ONDING IN S OLIDS 28

2.5 Bonding Forces and Energies 282.6 Primary Interatomic Bonds 302.7 Secondary Bonding or van der Waals Bonding 34Materials of Importance—Water (Its Volume Expansion Upon Freezing) 37

2.8 Molecules 38

Summary 38 Equation Summary 39 Processing/Structure/Properties/Performance Summary 40 Important Terms and Concepts 40

References 40 Questions and Problems 41

Contents

• xiii

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xiii

3 The Structure of Crystalline Solids 44

Learning Objectives 453.1 Introduction 45

C RYSTALLOGRAPHIC P OINTS , D IRECTIONS ,

Summary 80 Equation Summary 82 Processing/Structure/Properties/Performance Summary 83

Important Terms and Concepts 83 References 83

Questions and Problems 84

Learning Objectives 914.1 Introduction 91

Summary 114 Equation Summary 116 Processing/Structure/Properties/Performance Summary 117

Important Terms and Concepts 118 References 118

Questions and Problems 118 Design Problems 121

Learning Objectives 1235.1 Introduction 1235.2 Diffusion Mechanisms 1255.3 Steady-State Diffusion 1265.4 Nonsteady-State Diffusion 1285.5 Factors That Influence

Diffusion 1325.6 Diffusion in Semiconducting Materials 137

Materials of Importance—Aluminum forIntegrated Circuit Interconnects 1405.7 Other Diffusion Paths 142

Summary 142 Equation Summary 143 Processing/Structure/Properties/Performance Summary 144

Important Terms and Concepts 144 References 144

Questions and Problems 145 Design Problems 148

Learning Objectives 1516.1 Introduction 1516.2 Concepts of Stress and Strain 152

E LASTIC D EFORMATION 156

6.3 Stress–Strain Behavior 1566.4 Anelasticity 159

6.5 Elastic Properties of Materials 160

P LASTIC D EFORMATION 162

6.6 Tensile Properties 1626.7 True Stress and Strain 170JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xiv

6.8 Elastic Recovery After Plastic

Deformation 1736.9 Compressive, Shear, and Torsional

Deformations 1736.10 Hardness 174

P ROPERTY V ARIABILITY AND D ESIGN /S AFETY

F ACTORS 180

6.11 Variability of Material Properties 180

6.12 Design/Safety Factors 182

Summary 184 Equation Summary 186 Processing/Structure/Properties/Performance Summary 187

Important Terms and Concepts 188 References 188

Questions and Problems 188 Design Problems 195

7 Dislocations and Strengthening

Learning Objectives 1987.1 Introduction 198

D ISLOCATIONS AND P LASTIC

D EFORMATION 199

7.2 Basic Concepts 199

7.3 Characteristics of Dislocations 201

7.4 Slip Systems 202

7.5 Slip in Single Crystals 204

7.6 Plastic Deformation of Polycrystalline

Materials 2087.7 Deformation by Twinning 210

M ECHANISMS OF S TRENGTHENING IN

M ETALS 211

7.8 Strengthening by Grain Size

Reduction 2127.9 Solid-Solution Strengthening 213

Important Terms and Concepts 229 References 229

Questions and Problems 229 Design Problems 233

Learning Objectives 2358.1 Introduction 235

F RACTURE 236

8.2 Fundamentals of Fracture 2368.3 Ductile Fracture 236

8.4 Brittle Fracture 2398.5 Principles of Fracture Mechanics 2428.6 Fracture Toughness Testing 250

F ATIGUE 255

8.7 Cyclic Stresses 2558.8 The S–N Curve 2578.9 Crack Initiation and Propagation 2598.10 Factors That Affect Fatigue Life 2628.11 Environmental Effects 264

C REEP 265

8.12 Generalized Creep Behavior 2658.13 Stress and Temperature Effects 2668.14 Data Extrapolation Methods 2688.15 Alloys for High-Temperature Use 269

Summary 270 Equation Summary 273 Important Terms and Concepts 274 References 275

Questions and Problems 275 Design Problems 279

Learning Objectives 2829.1 Introduction 282

D EFINITIONS AND B ASIC C ONCEPTS 283

9.2 Solubility Limit 2839.3 Phases 284

9.4 Microstructure 2849.5 Phase Equilibria 2859.6 One-Component (or Unary) PhaseDiagrams 286

B INARY P HASE D IAGRAMS 287

9.7 Binary Isomorphous Systems 2879.8 Interpretation of Phase

Diagrams 2899.9 Development of Microstructure inIsomorphous Alloys 294

9.10 Mechanical Properties of IsomorphousAlloys 297

9.11 Binary Eutectic Systems 298Materials of Importance—Lead-FreeSolders 304

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xv

9.12 Development of Microstructure in

Eutectic Alloys 3059.13 Equilibrium Diagrams Having

Intermediate Phases or Compounds 3119.14 Eutectoid and Peritectic

Reactions 3139.15 Congruent Phase Transformations 315

9.16 Ceramic and Ternary Phase

Diagrams 3169.17 The Gibbs Phase Rule 316

T HE I RON –C ARBON S YSTEM 319

9.18 The Iron–Iron Carbide (Fe–Fe3C) Phase

Diagram 3199.19 Development of Microstructure in

Iron–Carbon Alloys 3229.20 The Influence of Other Alloying

Elements 330

Summary 331 Equation Summary 333 Processing/Structure/Properties/Performance Summary 334

Important Terms and Concepts 335 References 335

Questions and Problems 335

10 Phase Transformations: Development

of Microstructure and Alteration of

Learning Objectives 34310.1 Introduction 343

P HASE T RANSFORMATIONS 344

10.2 Basic Concepts 344

10.3 The Kinetics of Phase

Transformations 34410.4 Metastable Versus Equilibrium

States 355

M ICROSTRUCTURAL AND P ROPERTY C HANGES IN

I RON –C ARBON A LLOYS 356

10.5 Isothermal Transformation

Diagrams 35610.6 Continuous Cooling Transformation

Diagrams 36710.7 Mechanical Behavior of Iron–Carbon

Alloys 37010.8 Tempered Martensite 375

10.9 Review of Phase Transformations and

Mechanical Properties for Iron–CarbonAlloys 378

xvi • Contents

Materials of Importance—Shape-Memory Alloys 379

Summary 381 Equation Summary 383 Processing/Structure/Properties/Performance Summary 384

Important Terms and Concepts 385 References 385

Questions and Problems 385 Design Problems 390

11 Applications and Processing of Metal

Learning Objectives 39211.1 Introduction 392

T YPES OF M ETAL A LLOYS 393

11.2 Ferrous Alloys 39311.3 Nonferrous Alloys 406Materials of Importance—Metal AlloysUsed for Euro Coins 416

F ABRICATION OF M ETALS 417

11.4 Forming Operations 41711.5 Casting 419

11.6 Miscellaneous Techniques 420

T HERMAL P ROCESSING OF M ETALS 422

11.7 Annealing Processes 42211.8 Heat Treatment of Steels 42511.9 Precipitation Hardening 436

Summary 442 Processing/Structure/Properties/Performance Summary 444

Important Terms and Concepts 444 References 447

Questions and Problems 447 Design Problems 449

12 Structures and Properties of

Learning Objectives 45212.1 Introduction 452

C ERAMIC S TRUCTURES 453

12.2 Crystal Structures 45312.3 Silicate Ceramics 46412.4 Carbon 468

Materials of Importance—CarbonNanotubes 471

12.5 Imperfections in Ceramics 47212.6 Diffusion in Ionic Materials 47612.7 Ceramic Phase Diagrams 476JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xvi

Considerations 489

Summary 491 Equation Summary 494 Processing/Structure/Properties/Performance Summary 494

Important Terms and Concepts 495 References 495

Questions and Problems 495 Design Problems 500

13 Applications and Processing of

Learning Objectives 50213.1 Introduction 502

T YPES AND A PPLICATIONS OF C ERAMICS 503

F ABRICATION AND P ROCESSING OF

C ERAMICS 512

13.9 Fabrication and Processing of Glasses and

Glass-Ceramics 51313.10 Fabrication and Processing of Clay

Products 51813.11 Powder Pressing 523

13.12 Tape Casting 525

Summary 526 Processing/Structure/Properties/Performance Summary 528

Important Terms and Concepts 529 References 530

Questions and Problems 530 Design Problem 531

Learning Objectives 53314.1 Introduction 533

14.2 Hydrocarbon Molecules 534

Contents • xvii

14.3 Polymer Molecules 53514.4 The Chemistry of Polymer Molecules 537

14.5 Molecular Weight 54114.6 Molecular Shape 54414.7 Molecular Structure 54514.8 Molecular Configurations 54714.9 Thermoplastic and ThermosettingPolymers 550

14.10 Copolymers 55114.11 Polymer Crystallinity 55214.12 Polymer Crystals 55614.13 Defects in Polymers 55814.14 Diffusion in Polymeric Materials 559

Summary 561 Equation Summary 563 Processing/Structure/Properties/Performance Summary 564

Important Terms and Concepts 565 References 565

Questions and Problems 565

15 Characteristics, Applications, and

Learning Objectives 57015.1 Introduction 570

M ECHANICAL B EHAVIOR OF P OLYMERS 570

15.2 Stress–Strain Behavior 57015.3 Macroscopic Deformation 57315.4 Viscoelastic Deformation 57415.5 Fracture of Polymers 57815.6 Miscellaneous Mechanical Characteristics 580

M ECHANISMS OF D EFORMATION AND FOR

S TRENGTHENING OF P OLYMERS 581

15.7 Deformation of Semicrystalline Polymers 581

15.8 Factors That Influence the MechanicalProperties of Semicrystalline

Polymers 582Materials of Importance—Shrink-WrapPolymer Films 587

15.9 Deformation of Elastomers 588

C RYSTALLIZATION , M ELTING , AND G LASS

T RANSITION P HENOMENA IN P OLYMERS 590

15.10 Crystallization 59015.11 Melting 59215.12 The Glass Transition 59215.13 Melting and Glass TransitionTemperatures 592

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xvii

15.14 Factors That Influence Melting and Glass

Transition Temperatures 594

P OLYMER T YPES 596

15.15 Plastics 596

Materials of Importance—PhenolicBilliard Balls 598

15.16 Elastomers 599

15.17 Fibers 601

15.18 Miscellaneous Applications 601

15.19 Advanced Polymeric Materials 603

P OLYMER S YNTHESIS AND P ROCESSING 607

Important Terms and Concepts 620 References 620

Questions and Problems 621 Design Questions 625

Learning Objectives 62716.1 Introduction 627

P ARTICLE -R EINFORCED C OMPOSITES 629

16.2 Large-Particle Composites 630

16.3 Dispersion-Strengthened Composites 634

F IBER -R EINFORCED C OMPOSITES 634

16.4 Influence of Fiber Length 634

16.5 Influence of Fiber Orientation and

Concentration 63616.6 The Fiber Phase 645

16.7 The Matrix Phase 646

C ORROSION OF M ETALS 675

17.2 Electrochemical Considerations 67517.3 Corrosion Rates 682

17.4 Prediction of Corrosion Rates 68317.5 Passivity 690

17.6 Environmental Effects 69217.7 Forms of Corrosion 69217.8 Corrosion Environments 70017.9 Corrosion Prevention 70117.10 Oxidation 703

C ORROSION OF C ERAMIC M ATERIALS 706

Questions and Problems 715 Design Problems 718

Learning Objectives 72018.1 Introduction 720

E LECTRICAL C ONDUCTION 721

18.2 Ohm’s Law 72118.3 Electrical Conductivity 72118.4 Electronic and Ionic Conduction 72218.5 Energy Band Structures in Solids 72218.6 Conduction in Terms of Band and AtomicBonding Models 725

18.7 Electron Mobility 72718.8 Electrical Resistivity of Metals 72818.9 Electrical Characteristics of CommercialAlloys 731

Materials of Importance—AluminumElectrical Wires 731

JWCL187_fm_i-xxiv.qxd 11/17/09 1:11 PM Page xviii

Mobility 74218.14 The Hall Effect 746

18.15 Semiconductor Devices 748

E LECTRICAL C ONDUCTION IN I ONIC C ERAMICS AND IN P OLYMERS 754

18.16 Conduction in Ionic Materials 755

18.17 Electrical Properties of Polymers 756

Important Terms and Concepts 773 References 774

Questions and Problems 774 Design Problems 779

Learning Objectives 78219.1 Introduction 782

19.2 Heat Capacity 782

19.3 Thermal Expansion 785

Materials of Importance—Invar and Other Low-Expansion Alloys 788

19.4 Thermal Conductivity 789

19.5 Thermal Stresses 792

Summary 794 Equation Summary 795 Important Terms and Concepts 796 References 796

Questions and Problems 796 Design Problems 798

Learning Objectives 80120.1 Introduction 80120.2 Basic Concepts 80120.3 Diamagnetism and Paramagnetism 80520.4 Ferromagnetism 807

20.5 Antiferromagnetism and Ferrimagnetism 80920.6 The Influence of Temperature onMagnetic Behavior 813

20.7 Domains and Hysteresis 81420.8 Magnetic Anisotropy 81820.9 Soft Magnetic Materials 819Materials of Importance—An Iron–SiliconAlloy That Is Used in Transformer

Cores 82120.10 Hard Magnetic Materials 82220.11 Magnetic Storage 82520.12 Superconductivity 828

Summary 832 Equation Summary 834 Important Terms and Concepts 835 References 835

Questions and Problems 835 Design Problems 839

Learning Objectives 84121.1 Introduction 841

B ASIC C ONCEPTS 841

21.2 Electromagnetic Radiation 84121.3 Light Interactions with Solids 84321.4 Atomic and Electronic Interactions 844

O PTICAL P ROPERTIES OF M ETALS 845

O PTICAL P ROPERTIES OF N ONMETALS 846

21.5 Refraction 84621.6 Reflection 84821.7 Absorption 84921.8 Transmission 85221.9 Color 85321.10 Opacity and Translucency in Insulators 854

A PPLICATIONS OF O PTICAL P HENOMENA 855

21.11 Luminescence 855Materials of Importance—Light-EmittingDiodes 856

21.12 Photoconductivity 85821.13 Lasers 858

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21.14 Optical Fibers in Communications 863

Summary 865 Equation Summary 868 Important Terms and Concepts 869 References 869

Questions and Problems 869 Design Problem 871

22 Economic, Environmental, and

Societal Issues in Materials

Learning Objectives 87322.1 Introduction 873

Expansion A17B.7 Thermal Conductivity A21B.8 Specific Heat A24

B.9 Electrical Resistivity A26B.10 Metal Alloy Compositions A29

Appendix C Costs and Relative Costs for

Appendix D Repeat Unit Structures for

Appendix E Glass Transition and Melting Temperatures for Common Polymeric

The number of the section in which a symbol is introduced or explained is given

APF⫽ atomic packing factor (3.4)

a⫽ lattice parameter: unit cell

x-axial length (3.4)

a⫽ crack length of a surface crack(8.5)

at% ⫽ atom percent (4.4)

B⫽ magnetic flux density tion) (20.2)

(induc-B r⫽ magnetic remanence (20.7)BCC ⫽ body-centered cubic crystal

(17.3)CVN⫽ Charpy V-notch (8.6)

%CW⫽ percent cold work (7.10)

c⫽ lattice parameter: unit cell

z-axial length (3.7)

c⫽ velocity of electromagneticradiation in a vacuum (21.2)

d⫽ diameter

d⫽ average grain diameter (7.8)

d hkl⫽ interplanar spacing for planes of

Miller indices h, k, and l (3.16)

E⫽ energy (2.5)

E⫽ modulus of elasticity orYoung’s modulus (6.3)

e ⫽ electric field intensity (18.3)

logarithms

F⫽ force, interatomic or mechanical (2.5, 6.3)

f ⫽ Faraday constant (17.2)FCC⫽ face-centered cubic crystal

structure (3.4)

e⫺

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HK⫽ Knoop hardness (6.10)HRB, HRF⫽ Rockwell hardness: B and F

scales (6.10)HR15N, HR45W⫽superficial Rockwell hardness:

M⫽ magnetization (20.2)

⫽ polymer number-averagemolecular weight (14.5)

⫽ polymer weight-averagemolecular weight (14.5)mol%⫽ mole percent

N⫽ number of fatigue cycles (8.8)

NA⫽ Avogadro’s number (3.5)

N f⫽ fatigue life (8.8)

n⫽ principal quantum number (2.3)

n⫽ number of atoms per unit cell(3.5)

n⫽ strain-hardening exponent (6.7)

n⫽ number of electrons in anelectrochemical reaction (17.2)

n⫽ number of conducting trons per cubic meter (18.7)

elec-n⫽ index of refraction (21.5)

M w

M n

xxii • List of Symbols

n⬘ ⫽ for ceramics, the number offormula units per unit cell(12.2)

n i⫽ intrinsic carrier (electron andhole) concentration (18.10)

P⫽ dielectric polarization (18.19)P–B ratio ⫽ Pilling–Bedworth ratio (17.10)

p⫽ number of holes per cubicmeter (18.10)

T g⫽ glass transition temperature(13.9, 15.12)

T m⫽ melting temperatureTEM⫽ transmission electron

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W i ⫽ mass fraction of phase i (9.8)

wt%⫽ weight percent (4.4)

x⫽ length

x⫽ space coordinate

Y⫽ dimensionless parameter orfunction in fracture toughnessexpression (8.5)

␳ ⫽ density (3.5)

nn

␶crss⫽ critical resolved shear stress(7.5)

⫽ magnetic susceptibility (20.2)

SUBSCRIPTS

c⫽ composite

cd⫽ discontinuous fibrous composite

cl⫽ longitudinal direction (alignedfibrous composite)

ct⫽ transverse direction (alignedfibrous composite)

0⫽ original

0⫽ at equilibrium

0⫽ in a vacuum

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• 1

C h a p t e r 1 Introduction

Afamiliar item that is fabricated from three different material types is the beverage container Beverages are marketed in aluminum (metal) cans (top), glass (ceramic) bottles (center), and plastic (polymer) bottles (bottom) (Permission to use these photographs was granted by the Coca-Cola Company Coca-Cola, Coca-Cola Classic, the Contour Bottle design and the Dynamic Ribbon are registered trademarks of The Coca-Cola Company and used with its express permission Soda being poured from a glass: © blickwinkel/Alamy.) JWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 1

1.1 HISTORICAL PERSPECTIVE

Materials are probably more deep-seated in our culture than most of us realize.Transportation, housing, clothing, communication, recreation, and food production—virtually every segment of our everyday lives is influenced to one degree or another

by materials Historically, the development and advancement of societies have beenintimately tied to the members’ ability to produce and manipulate materials to filltheir needs In fact, early civilizations have been designated by the level of theirmaterials development (Stone Age, Bronze Age, Iron Age).1

The earliest humans had access to only a very limited number of materials,those that occur naturally: stone, wood, clay, skins, and so on With time they dis-covered techniques for producing materials that had properties superior to those

of the natural ones; these new materials included pottery and various metals thermore, it was discovered that the properties of a material could be altered byheat treatments and by the addition of other substances At this point, materials uti-lization was totally a selection process that involved deciding from a given, ratherlimited set of materials the one best suited for an application by virtue of its char-acteristics It was not until relatively recent times that scientists came to understandthe relationships between the structural elements of materials and their properties.This knowledge, acquired over approximately the past 100 years, has empoweredthem to fashion, to a large degree, the characteristics of materials Thus, tens of thou-sands of different materials have evolved with rather specialized characteristics thatmeet the needs of our modern and complex society; these include metals, plastics,glasses, and fibers

Fur-The development of many technologies that make our existence so fortable has been intimately associated with the accessibility of suitable materials

com-An advancement in the understanding of a material type is often the runner to the stepwise progression of a technology For example, automobileswould not have been possible without the availability of inexpensive steel orsome other comparable substitute In our contemporary era, sophisticated elec-tronic devices rely on components that are made from what are called semicon-ducting materials

fore-L e a r n i n g O b j e c t i v e s

After studying this chapter you should be able to do the following:

1 List six different property classifications of

materials that determine their applicability

2 Cite the four components that are involved in

the design, production, and utilization ofmaterials, and briefly describe the interrelation-ships between these components

3 Cite three criteria that are important in the

materials selection process

4 (a) List the three primary classifications of

solid materials, and then cite the distinctivechemical feature of each

(b) Note the four types of advanced materialsand, for each, its distinctive feature(s)

5 (a) Briefly define “smart material/system.”

(b) Briefly explain the concept of nology” as it applies to materials

“nanotech-1 The approximate dates for the beginnings of the Stone, Bronze, and Iron Ages were 2.5 million BC , 3500 BC , and 1000 BC , respectively.

2 •

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1.2 MATERIALS SCIENCE AND ENGINEERING

Sometimes it is useful to subdivide the discipline of materials science and

engi-neering into materials science and materials engiengi-neering subdisciplines Strictly

speaking, materials science involves investigating the relationships that exist tween the structures and properties of materials In contrast, materials engineering

be-is, on the basis of these structure–property correlations, designing or engineeringthe structure of a material to produce a predetermined set of properties.2From afunctional perspective, the role of a materials scientist is to develop or synthesizenew materials, whereas a materials engineer is called upon to create new products

or systems using existing materials, and/or to develop techniques for processingmaterials Most graduates in materials programs are trained to be both materialsscientists and materials engineers

Structure is at this point a nebulous term that deserves some explanation In

brief, the structure of a material usually relates to the arrangement of its internalcomponents Subatomic structure involves electrons within the individual atoms andinteractions with their nuclei On an atomic level, structure encompasses the or-ganization of atoms or molecules relative to one another The next larger structuralrealm, which contains large groups of atoms that are normally agglomerated to-

gether, is termed microscopic, meaning that which is subject to direct observation

using some type of microscope Finally, structural elements that may be viewed with

the naked eye are termed macroscopic.

The notion of property deserves elaboration While in service use, all materials

are exposed to external stimuli that evoke some type of response For example, aspecimen subjected to forces will experience deformation, or a polished metal surfacewill reflect light A property is a material trait in terms of the kind and magnitude ofresponse to a specific imposed stimulus Generally, definitions of properties aremade independent of material shape and size

Virtually all important properties of solid materials may be grouped into sixdifferent categories: mechanical, electrical, thermal, magnetic, optical, and deterio-rative For each there is a characteristic type of stimulus capable of provoking dif-ferent responses Mechanical properties relate deformation to an applied load orforce; examples include elastic modulus (stiffness), strength, and toughness For elec-trical properties, such as electrical conductivity and dielectric constant, the stimu-lus is an electric field The thermal behavior of solids can be represented in terms

of heat capacity and thermal conductivity Magnetic properties demonstrate the sponse of a material to the application of a magnetic field For optical properties,the stimulus is electromagnetic or light radiation; index of refraction and reflectiv-ity are representative optical properties Finally, deteriorative characteristics relate

re-to the chemical reactivity of materials The chapters that follow discuss propertiesthat fall within each of these six classifications

In addition to structure and properties, two other important components are

involved in the science and engineering of materials—namely, processing and

per-formance With regard to the relationships of these four components, the structure

of a material will depend on how it is processed Furthermore, a material’s formance will be a function of its properties Thus, the interrelationship betweenprocessing, structure, properties, and performance is as depicted in the schematic

per-1.2 Materials Science and Engineering • 3

2 Throughout this text we draw attention to the relationships between material properties and structural elements.

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4 • Chapter 1 / Introduction

illustration shown in Figure 1.1 Throughout this text we draw attention to therelationships among these four components in terms of the design, production, andutilization of materials

We now present an example of these processing-structure-properties-performanceprinciples with Figure 1.2, a photograph showing three thin disk specimens placedover some printed matter It is obvious that the optical properties (i.e., the light trans-mittance) of each of the three materials are different; the one on the left is trans-parent (i.e., virtually all of the reflected light passes through it), whereas the disks inthe center and on the right are, respectively, translucent and opaque All of these spec-imens are of the same material, aluminum oxide, but the leftmost one is what we call

a single crystal—that is, has a high degree of perfection—which gives rise to its parency The center one is composed of numerous and very small single crystals thatare all connected; the boundaries between these small crystals scatter a portion of thelight reflected from the printed page, which makes this material optically translucent.Finally, the specimen on the right is composed not only of many small, interconnectedcrystals, but also of a large number of very small pores or void spaces These poresalso effectively scatter the reflected light and render this material opaque

trans-Thus, the structures of these three specimens are different in terms of crystalboundaries and pores, which affect the optical transmittance properties Further-more, each material was produced using a different processing technique And, ofcourse, if optical transmittance is an important parameter relative to the ultimatein-service application, the performance of each material will be different

Figure 1.1 The four components of the discipline of materials science and engineering and their interrelationship.

Processing Structure Properties Performance

Figure 1.2 Three thin disk specimens of aluminum oxide that have been placed over a printed page in order to demonstrate their differences in light-transmittance characteristics The disk on the left is transparent (i.e., virtually all light that is reflected from the page passes through it), whereas the one in the center is translucent (meaning that some of this reflected light is transmitted through the disk) The disk on the right is opaque—that is, none

of the light passes through it These differences in optical properties are a consequence of differences in structure of these materials, which have resulted from the way the materials were processed (Specimen preparation, P A Lessing; photography by S Tanner.)

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1.3 WHY STUDY MATERIALS SCIENCE

AND ENGINEERING?

Why do we study materials? Many an applied scientist or engineer, whether chanical, civil, chemical, or electrical, will at one time or another be exposed to adesign problem involving materials Examples might include a transmission gear,the superstructure for a building, an oil refinery component, or an integrated cir-cuit chip Of course, materials scientists and engineers are specialists who are to-tally involved in the investigation and design of materials

me-Many times, a materials problem is one of selecting the right material from thethousands that are available The final decision is normally based on several criteria.First of all, the in-service conditions must be characterized, for these will dictate theproperties required of the material On only rare occasions does a material possessthe maximum or ideal combination of properties Thus, it may be necessary to tradeone characteristic for another The classic example involves strength and ductility;normally, a material having a high strength will have only a limited ductility In suchcases a reasonable compromise between two or more properties may be necessary

A second selection consideration is any deterioration of material propertiesthat may occur during service operation For example, significant reductions in me-chanical strength may result from exposure to elevated temperatures or corrosiveenvironments

Finally, probably the overriding consideration is that of economics: What willthe finished product cost? A material may be found that has the ideal set of prop-erties but is prohibitively expensive Here again, some compromise is inevitable.The cost of a finished piece also includes any expense incurred during fabrication

to produce the desired shape

The more familiar an engineer or scientist is with the various characteristicsand structure–property relationships, as well as processing techniques of materials,the more proficient and confident he or she will be in making judicious materialschoices based on these criteria

1.4 CLASSIFICATION OF MATERIALS

Solid materials have been conveniently grouped into three basic categories: als, ceramics, and polymers This scheme is based primarily on chemical makeupand atomic structure, and most materials fall into one distinct grouping or another

met-In addition, there are the composites, which are engineered combinations of two

or more different materials A brief explanation of these material classificationsand representative characteristics is offered next Another category is advancedmaterials—those used in high-technology applications, such as semiconductors, bio-materials, smart materials, and nanoengineered materials; these are discussed inSection 1.5

Metals

Materials in this group are composed of one or more metallic elements (e.g., iron,aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements(e.g., carbon, nitrogen, and oxygen) in relatively small amounts.3Atoms in metals andtheir alloys are arranged in a very orderly manner (as discussed in Chapter 3), and

in comparison to the ceramics and polymers, are relatively dense (Figure 1.3) With

1.4 Classification of Materials • 5

3The term metal alloy refers to a metallic substance that is composed of two or more

elements.

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6 • Chapter 1 / Introduction

regard to mechanical characteristics, these materials are relatively stiff (Figure 1.4)and strong (Figure 1.5), yet are ductile (i.e., capable of large amounts of deformationwithout fracture), and are resistant to fracture (Figure 1.6), which accounts for theirwidespread use in structural applications Metallic materials have large numbers ofnonlocalized electrons; that is, these electrons are not bound to particular atoms Manyproperties of metals are directly attributable to these electrons For example, metalsare extremely good conductors of electricity (Figure 1.7) and heat, and are not trans-parent to visible light; a polished metal surface has a lustrous appearance In addi-tion, some of the metals (i.e., Fe, Co, and Ni) have desirable magnetic properties.Figure 1.8 shows several common and familiar objects that are made of metal-lic materials Furthermore, the types and applications of metals and their alloys arediscussed in Chapter 11

2

1.0

0.6

0.2 0.4

0.1

Metals

Platinum

Silver Copper Iron/Steel Titanium

Aluminum Magnesium

Composites GFRC CFRC

Woods

Polymers

PTFE PVC PS PE Rubber

ZrO2

Al2O3SiC, Si3N4Glass Concrete Ceramics

10

1.0

0.1

100 1000

0.01

Composites

GFRC CFRC

Woods Polymers

PVC

PTFE PE

Rubbers

PS, Nylon

Metals

Tungsten Iron/Steel

Aluminum Magnesium Titanium

Ceramics

SiC

AI2O3

Si3N4ZrO2Glass Concrete

Figure 1.4

Bar chart of

room-temperature stiffness

(i.e., elastic modulus)

values for various metals, ceramics, polymers, and composite materials.

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1.4 Classification of Materials • 7

1000

100

10

Nylon PS

PE

PVC

PTFE Polymers

Steel alloys

Gold

Aluminum alloys

Cu,Ti alloys

Metals

CFRC GFRC Composites

Woods Glass

Si3N4SiC Ceramics

Al2O3

Figure 1.5

Bar chart of temperature strength

room-(i.e., tensile strength)

values for various metals, ceramics, polymers, and composite materials.

Wood

Nylon Polymers

Polystyrene Polyethylene

Polyester

Al2O3SiC

Si3N4

Glass

Concrete Ceramics

Metals

Steel alloys Titanium alloys Aluminum alloys

Figure 1.6 Bar chart of room-temperature resistance to fracture (i.e., fracture toughness)

for various metals, ceramics, polymers, and composite materials (Reprinted from Engineering

Materials 1: An Introduction to Properties, Applications and Design, third edition, M F Ashby

and D R H Jones, pages 177 and 178, Copyright 2005, with permission from Elsevier.)

include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), siliconcarbide (SiC), silicon nitride (Si3N4), and, in addition, what some refer to as the tra-

ditional ceramics—those composed of clay minerals (i.e., porcelain), as well as

cement and glass With regard to mechanical behavior, ceramic materials are relativelystiff and strong—stiffnesses and strengths are comparable to those of the metals(Figures 1.4 and 1.5) In addition, they are typically very hard Historically, ceramicshave exhibited extreme brittleness (lack of ductility) and are highly susceptible to frac-ture (Figure 1.6) However, newer ceramics are being engineered to have improvedresistance to fracture; these materials are used for cookware, cutlery, and even auto-mobile engine parts Furthermore, ceramic materials are typically insulative to the pas-sage of heat and electricity (i.e., have low electrical conductivities, Figure 1.7), and aremore resistant to high temperatures and harsh environments than metals and polymers.JWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 7

8 • Chapter 1 / Introduction

With regard to optical characteristics, ceramics may be transparent, translucent, oropaque (Figure 1.2), and some of the oxide ceramics (e.g., Fe3O4) exhibit magneticbehavior

Several common ceramic objects are shown in Figure 1.9 The characteristics,types, and applications of this class of materials are discussed in Chapters 12 and 13

Polymers

Polymers include the familiar plastic and rubber materials Many of them are organiccompounds that are chemically based on carbon, hydrogen, and other nonmetallicelements (i.e., O, N, and Si) Furthermore, they have very large molecular structures,often chainlike in nature, that often have a backbone of carbon atoms Some of thecommon and familiar polymers are polyethylene (PE), nylon, poly(vinyl chloride)(PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber.These materials typ-ically have low densities (Figure 1.3), whereas their mechanical characteristics are gen-erally dissimilar to the metallic and ceramic materials—they are not as stiff nor asstrong as these other material types (Figures 1.4 and 1.5) However, on the basis of

for metals, ceramics,

polymers, and semiconducting materials.

Figure 1.8 Familiar objects that are made of metals and metal alloys (from left to right): silverware (fork and knife), scissors, coins, a gear, a wedding ring, and a nut and bolt.

JWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 8

their low densities, many times their stiffnesses and strengths on a per-mass basis arecomparable to the metals and ceramics In addition, many of the polymers areextremely ductile and pliable (i.e., plastic), which means they are easily formed intocomplex shapes In general, they are relatively inert chemically and unreactive in alarge number of environments One major drawback to the polymers is their tendency

to soften and/or decompose at modest temperatures, which, in some instances, limitstheir use Furthermore, they have low electrical conductivities (Figure 1.7) and arenonmagnetic

Figure 1.10 shows several articles made of polymers that are familiar to thereader Chapters 14 and 15 are devoted to discussions of the structures, properties,applications, and processing of polymeric materials

1.4 Classification of Materials • 9

Figure 1.9

Common objects that are made of ceramic materials: scissors, a china teacup, a building brick, a floor tile, and a glass vase.

Figure 1.10

Several common objects that are made of polymeric materials: plastic tableware (spoon, fork, and knife), billiard balls, a bicycle helmet, two dice, a lawn mower wheel (plastic hub and rubber tire), and a plastic milk carton.

JWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 9

by any single material, and also to incorporate the best characteristics of each ofthe component materials A large number of composite types are represented bydifferent combinations of metals, ceramics, and polymers Furthermore, somenaturally occurring materials are composites—for example, wood and bone How-ever, most of those we consider in our discussions are synthetic (or human-made)composites.

One of the most common and familiar composites is fiberglass, in which smallglass fibers are embedded within a polymeric material (normally an epoxy or poly-ester).4The glass fibers are relatively strong and stiff (but also brittle), whereas thepolymer is more flexible Thus, fiberglass is relatively stiff, strong (Figures 1.4 and1.5), and flexible In addition, it has a low density (Figure 1.3)

Another technologically important material is the carbon fiber–reinforced mer (CFRP) composite—carbon fibers that are embedded within a polymer Thesematerials are stiffer and stronger than glass fiber–reinforced materials (Figures 1.4and 1.5), but more expensive CFRP composites are used in some aircraft and

poly-4 Fiberglass is sometimes also termed a “glass fiber–reinforced polymer” composite, viated GFRP.

abbre-One common item that presents some

inter-esting material property requirements is thecontainer for carbonated beverages The material

used for this application must satisfy the

follow-ing constraints: (1) provide a barrier to the

pas-sage of carbon dioxide, which is under pressure

in the container; (2) be nontoxic, unreactive with

the beverage, and, preferably, recyclable; (3) be

relatively strong and capable of surviving a drop

from a height of several feet when containing the

beverage; (4) be inexpensive, including the cost to

fabricate the final shape; (5) if optically

transpar-ent, retain its optical clarity; and (6) be capable

of being produced in different colors and/or

adorned with decorative labels

All three of the basic material types—metal(aluminum), ceramic (glass), and polymer (poly-

ester plastic)—are used for carbonated beverage

containers (per the chapter-opening photographs

for this chapter) All of these materials are

non-toxic and unreactive with beverages In addition,each material has its pros and cons For example,the aluminum alloy is relatively strong (but easilydented), is a very good barrier to the diffusion ofcarbon dioxide, is easily recycled, cools beveragesrapidly, and allows labels to be painted onto its sur-face On the other hand, the cans are opticallyopaque and relatively expensive to produce Glass

is impervious to the passage of carbon dioxide, is

a relatively inexpensive material, and may be cycled, but it cracks and fractures easily, and glassbottles are relatively heavy Whereas plastic is rel-atively strong, may be made optically transparent,

re-is inexpensive and lightweight, and re-is recyclable, it

is not as impervious to the passage of carbon ide as the aluminum and glass For example, youmay have noticed that beverages in aluminum andglass containers retain their carbonization (i.e.,

diox-“fizz”) for several years, whereas those in two-literplastic bottles “go flat” within a few months.JWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 10

1.5 Advanced Materials • 11

aerospace applications, as well as high-tech sporting equipment (e.g., bicycles, golfclubs, tennis rackets, and skis/snowboards) and recently in automobile bumpers Thenew Boeing 787 fuselage is primarily made from such CFRP composites

Chapter 16 is devoted to a discussion of these interesting composite materials

1.5 ADVANCED MATERIALS

Materials that are utilized in high-technology (or high-tech) applications are

some-times termed advanced materials By high technology we mean a device or product

that operates or functions using relatively intricate and sophisticated principles; amples include electronic equipment (camcorders, CD/DVD players, etc.), com-puters, fiber-optic systems, spacecraft, aircraft, and military rocketry.These advancedmaterials are typically traditional materials whose properties have been enhanced,and also newly developed, high-performance materials Furthermore, they may be

ex-of all material types (e.g., metals, ceramics, polymers), and are normally expensive.Advanced materials include semiconductors, biomaterials, and what we may term

“materials of the future” (that is, smart materials and nanoengineered materials),which we discuss next The properties and applications of a number of theseadvanced materials—for example, materials that are used for lasers, integratedcircuits, magnetic information storage, liquid crystal displays (LCDs), and fiberoptics—are also discussed in subsequent chapters

Semiconductors

Semiconductors have electrical properties that are intermediate between the trical conductors (i.e., metals and metal alloys) and insulators (i.e., ceramics andpolymers)—see Figure 1.7 Furthermore, the electrical characteristics of these ma-terials are extremely sensitive to the presence of minute concentrations of impu-rity atoms, for which the concentrations may be controlled over very small spatialregions Semiconductors have made possible the advent of integrated circuitry thathas totally revolutionized the electronics and computer industries (not to mentionour lives) over the past three decades

elec-Biomaterials

Biomaterials are employed in components implanted into the human body to place diseased or damaged body parts These materials must not produce toxic sub-stances and must be compatible with body tissues (i.e., must not cause adversebiological reactions) All of the preceding materials—metals, ceramics, polymers,composites, and semiconductors—may be used as biomaterials For example, some

re-of the biomaterials that are utilized in artificial hip replacements are discussed inthe online Biomaterials Module

Smart Materials

Smart (or intelligent) materials are a group of new and state-of-the-art materials

now being developed that will have a significant influence on many of our

tech-nologies The adjective smart implies that these materials are able to sense changes

in their environment and then respond to these changes in predeterminedmanners—traits that are also found in living organisms In addition, this “smart”concept is being extended to rather sophisticated systems that consist of both smartand traditional materials

Components of a smart material (or system) include some type of sensor (thatdetects an input signal), and an actuator (that performs a responsive and adaptiveJWCL187_ch01_001-017.qxd 11/5/09 1:46 PM Page 11

12 • Chapter 1 / Introduction

5 One legendary and prophetic suggestion as to the possibility of nanoengineered materials was offered by Richard Feynman in his 1959 American Physical Society lecture titled

“There’s Plenty of Room at the Bottom.”

function) Actuators may be called upon to change shape, position, natural quency, or mechanical characteristics in response to changes in temperature, elec-tric fields, and/or magnetic fields

fre-Four types of materials are commonly used for actuators: shape-memory alloys,piezoelectric ceramics, magnetostrictive materials, and electrorheological/magne-torheological fluids Shape-memory alloys are metals that, after having been de-formed, revert back to their original shape when temperature is changed (see theMaterials of Importance box following Section 10.9) Piezoelectric ceramics expandand contract in response to an applied electric field (or voltage); conversely, theyalso generate an electric field when their dimensions are altered (see Section 18.25).The behavior of magnetostrictive materials is analogous to that of the piezoelectrics,except that they are responsive to magnetic fields Also, electrorheological and mag-netorheological fluids are liquids that experience dramatic changes in viscosity uponthe application of electric and magnetic fields, respectively

Materials/devices employed as sensors include optical fibers (Section 21.14),piezoelectric materials (including some polymers), and microelectromechanical sys-tems (MEMS, Section 13.8)

For example, one type of smart system is used in helicopters to reduce dynamic cockpit noise that is created by the rotating rotor blades Piezoelectricsensors inserted into the blades monitor blade stresses and deformations; feedbacksignals from these sensors are fed into a computer-controlled adaptive device, whichgenerates noise-canceling antinoise

aero-Nanomaterials

One new material class that has fascinating properties and tremendous

technolog-ical promise is the nanomaterials Nanomaterials may be any one of the four basic

types—metals, ceramics, polymers, and composites However, unlike these other terials, they are not distinguished on the basis of their chemistry, but rather, size;

ma-the nano-prefix denotes that ma-the dimensions of ma-these structural entities are on ma-the

order of a nanometer (10–9m)—as a rule, less than 100 nanometers (equivalent toapproximately 500 atom diameters)

Prior to the advent of nanomaterials, the general procedure scientists used tounderstand the chemistry and physics of materials was to begin by studying largeand complex structures, and then to investigate the fundamental building blocks ofthese structures that are smaller and simpler This approach is sometimes termed

“top-down” science On the other hand, with the development of scanning probemicroscopes (Section 4.10), which permit observation of individual atoms and mol-ecules, it has become possible to design and build new structures from their atomic-level constituents, one atom or molecule at a time (i.e., “materials by design”) Thisability to carefully arrange atoms provides opportunities to develop mechanical,electrical, magnetic, and other properties that are not otherwise possible We callthis the “bottom-up” approach, and the study of the properties of these materials

is termed nanotechnology.5

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